send_message

SERVERMeridian SOURCE@meridianmcp/mcp

Medium RISK CLASS

Category Write

Parameters 62 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-ajc3xc-meridian/send-message.md

WHAT IT DOES

What send_message does on Meridian

AI agents use send_message to create or update resources in Meridian, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Meridian environment.

Parameter	Type	Required	Description
`kind`	string	—	Optional message kind/tag.
`payload`	string	Yes	Message body (text or JSON).
`project_id`	string	—
`project_name`	string	—	Project name — an alternative to project_id.
`to_session_id`	string	Yes	Recipient session id.
`from_session_id`	string	—	Sender session id (defaults to session_id).

Parameters from the server's own tool schema.

RISK

Why send_message is rated Medium

This tool creates and persists new data (messages and metadata) in a database table, making it a Write operation. Severity is medium because stored messages could contain sensitive project context or coordination instructions visible to other sessions, but the action is reversible (the description hints at deletion support).

From the tool's definition Tool enqueues messages to session_messages table and stores text and metadata persistently. Description states: 'enqueue an actor-model message to another session (session_messages table)' and 'supplied text and project/session metadata are sent to and stored…

Risk signalsAccepts raw HTML/template content (payload)

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs send_message safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Meridian, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For send_message, this is the rule to start with:

send_message Rate-limited

send_message stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "send_message": {
      "limits": [
        {
          "counter": "send_message_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Meridian, apply this rule, and every send_message call is checked against it from then on.

FAQ

Questions about send_message

What does the send_message tool do? +

[MAINTENANCE] PARALLEL COORDINATION (d3a3a01d): enqueue an actor-model message to another session (session_messages table). 'Done with X, you do Y' between parallel agents. The recipient reads with receive_messages. A2A-compatible. Persistent-state disclosure: on hosted Meridian, supplied text and project/session metadata are sent to and stored in Meridian's service; self-hosted deployments keep them in the configured local SQLite/Postgres database. This data is visible in the dashboard/API and later project context or handoffs. Delete individual tasks, notes, or decisions where supported, or delete the project/account using the documented controls. Do not include secrets. It is categorised as a Write tool in the Meridian MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does send_message accept? +

send_message accepts 6 parameters: kind, payload, project_id, project_name, to_session_id, from_session_id. Required: payload, to_session_id. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on send_message? +

Register the Meridian MCP server in PolicyLayer and add a rule for send_message: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Meridian. Nothing to install.

What risk level is send_message? +

send_message is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit send_message? +

Yes. Add a rate_limit block to the send_message rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block send_message completely? +

Set action: deny in the PolicyLayer policy for send_message. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides send_message? +

send_message is provided by the Meridian MCP server (@meridianmcp/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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